Clean up TODO comments for new room list

All relevant TODOs should still be present, and reference an issue for easy finding.

src/components/structures/UserMenu.tsx

@@ -136,7 +136,7 @@ export default class UserMenu extends React.Component<IProps, IState> {
         ev.preventDefault();
         ev.stopPropagation();
 
-        // TODO: Archived room view (deferred)
+        // TODO: Archived room view: https://github.com/vector-im/riot-web/issues/14038
         console.log("TODO: Show archived rooms");
     };